Are you using the correct flag values when using LoadImage/LoadAnimImage/CreateImage etc? To preserve the images after an ALT-TAB, you need to either use managed mode or reload the images manually.
From the documentation:
From the documentation:
1 : managed (image is frequently drawn but seldom modified - this is the default) 2 : dynamic (image is frequently drawn and modified) 4 : scratch (image is seldom drawn or modified) Managed images are the default. Dynamic images are the fastest, but can be 'lost' when the display mode changes. This means the contents of the image will be scrambled, and you will need to restore the image content. If you are frequently redrawing the image contents, this isn't really a problem. If not, you should use managed images!I hope this helps.